End of car cushioning unit

ABSTRACT

A hydraulic end of car cushioning device for use in railway freight cars. The device is intended for use between the coupler shank and car underframe of a fixed sill type car and is designed so as to provide a long cushioning stroke under high impact loads. A load responsive check valve is interposed in the metering system of the cushioning device for preventing changes in length of the unit under lower buff and draft forces as occur in train action.

United States Patent [1 1 MacCurdy Dec. 30, 1975 [54] END OF CARCUSHIONING UNIT [75] Inventor: William K. MacCurdy, Plymouth,

Mich.

[73] Assignee: Evans Products Company,

Plymouth, Mich.

[22] Filed: Aug. 13, 1973 [21] Appl. No.: 388,330

[52] US. Cl 213/43; 213/8 [51] Int. Cl. B6lg 11/12 [58] Field of Search213/43, 8; 267/64 B, 64 A;

[56] References Cited UNITED STATES PATENTS 3,493,124 2/1970 Thompson213/43 2/1972 Carlson et al 213/43 X 4/1973 Brambilla et a1. 213/43 XPrimary ExaminerLloyd L. King Assistant Examiner-Michael Mar Attorney,Agent, or Firml-larness, Dickey & Pierce [57] ABSTRACT 14 Claims, 3Drawing Figures US. Patent Dec. 30, 1975 $& \1

END OF CAR CUSHIONING UNIT BACKGROUND OF THE INVENTION This inventionrelates to a cushioning unit and more particularly to a. cushioning unitadapted for use at the ends of railway cars.

It has been the practice to upgrade existing, fixed sill railway cars byproviding them with end of car cushioning devices. Hydraulic cushioningunits have been proposed for this purpose. The cushioning unit, however,experiences widely differing types of loadings. When making up a trainin a switching or classification yard, the car receives extreme shockloadings due to high velocity impacts. Under such conditions, it isdesirable to provide an extremely long cushioning stroke to effectivelyabsorb these impacts. Long stroke end of car cushioning units, however,are not desirable when the train has been made up and is in transit. Theunits have a tendency to extend the length of the train considerablyduring these conditions and cause considerable problems when the slackis taken up.

It is, therefore, a principal object of this invention to provide animproved end of car cushioning unit.

Another object of the invention is to provide an end of car cushioningunit that provides a long stroke under high impacts but which resistschanges in length under lower loading.

It is a further object of the invention to provide an end of carcushioning unit that requires a predetermined force to be applied to itbefore its cushioning operation becomes effective.

SUMMARY OF THE INVENTION This invention is adapted to be embodied in anend of car cushioning unit that is adapted to be interposed between acoupler and the frame of a railway car for damping shock forces. Thecushioning unit comprises a cylinder and a piston received within thecylinder and defining with the cylinder a chamber that is adapted toreceive a fluid. Primary metering means adapted to pass fluid from thechamber at a restricted rate upon relative movement of the piston andthe cylinder. Means are provided for precluding the flow of fluidthrough theprimary metering means until a predetermined force is appliedto the cushioning unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinalcross-sectional view taken through the end of a railway car having acushioning unit embodying this invention with the car structure beingshown in phantom.

FIG. 2 is an enlarged view showing the metering device of the cushioningunit as it appears under buff forces.

FIG. 3 is an enlarged view, in part similar to FIG. 2, showing thedevice as it appears when it experiences draft forces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates anend of car cushioning unit embodying this invention, identifiedgenerally by the reference numeral 11. The end of car cushioning unit 11is adapted to be interposed between a coupler shank 12 and the carunder-frame 13. The installation may be accomplished in any of a varietyof manners and, for this reason, the car structure has been shown onlyin phantom. Certain details of the illustrated installation will bedescribed, but should only be considered as exemplary in nature.

The cushioning unit 11 includes a cylinder assembly 14 comprised of acylinder head 15, a tubular cylinder 16 and a closure plug 17. Thecylinder 16 defines a cylindrical bore 18 closed at one end by thecylinder head 15 and at the other end by the plug 17 to define a fluidreceiving chamber 19.

The chamber 19 is divided into two sections by means of a pistonassembly 21 that is slidably supported within the bore 18. The pistonassembly 21 includes an orifice plate 22 that is affixed to a mainpiston 23 by means of bolts 24, only one of which appears in thedrawings. An anti-friction bushing 25 engages the bore 18 and is trappedbetween outstanding flanges of the orifice plate 22 and the main piston23. The piston 23 is also formed with an annular groove 26 in which apiston ring 27 is positioned to sealingly engage the bore 18.

A piston rod 28 is affixed in any known manner to the piston assembly 21and extends through an opening 29 formed in the closure plug 17. Abushing 31 and seal assembly 32 carried by the closure plug 17 supportsand sealingly engages the piston rod 28.

The piston rod 28 has affixed to its outer end a draft collar 33 that istrapped in a draft lug assembly, indicated by the reference numeral 34that is fixed in any suitable manner to the under-frame of theassociated railway car. The cooperation of the draft lug assembly 34with the draft collar 33 couples the piston rod 28 and piston assembly21 to the car under-frame 13. That is, the piston assembly 21 is heldagainst any substantial movement relative to the under-frame structure13.

The cylinder head 15 is formed at its outer end with a socket 35 thatreceives the coupler shank 12. Alligned openings 36 and 37 are formed onopposite sides of the socket 35 to receive a draft key (not shown) forfixing the coupler shank to the cylinder head 15. Thus, the cylinderassembly 14 is affixed for movement with the coupler shank 12. A stopblock 38 is fixed to the under-frame 13 and is abuttingly engaged by thecylinder head 15 when the cushioning unit 11 is in its fully extendeddraft position (FIG. 1).

A metering rod 39 of predetermined configuration is affixed to thecylinder head 15 and extends concentrically into the cavity 19. Anappropriately sized orifice opening 41 is formed in the orifice plate 22for cooperation with the metering rod 39. The piston rod 28 is formedwith an elongated cylindrical opening 42 that is alligned with theorifice opening 41 and which is adapted to receive, without restriction,the metering rod 39 at the extreme position of the piston assembly 21relative to the cylinder assembly 14 in the buff condition.

In order to preclude relative movement of the piston assembly 21 andcylinder assembly 14 until large impact forces are received, there: isprovided a pressure responsive valve assembly, indicated generally bythe reference numeral 43 and shown in most detail in FIGS. 2 and 3. Thepressure responsive valve assembly 43 includes one or more passages 44that extend axially through the piston 23 between a cavity 45 formedbetween the main piston 23 and orifice plate 22 and an annular relief 46formed in the main piston 23. The flow through the passage 44 iscontrolled by a conical disk spring valve member 47. In the non-flowcondition the outer peripheral edge 48 of the valve member 47 sealinglyengages the main piston 23. An opposite peripheral edge 49 sealinglyengages a collar 51 that is received around a recess 52 at the outer endof the piston rod 28 and which is axially held in position by the mainpiston 23. As will become apparent, the valve member 47 acts as atwo-way, pressure responsive valve.

The chamber 19 is partially filled with hydraulic fluid to a levelindicated by the phantom line 53. Gas, such as Nitrogen, at a highpressure is charged into the cavity 19 above the oil level 53. The gaspressure acts as a return spring to hold the cushioning unit 11 in theposition shown in FIG. 1. For a reason which will be come more apparent,one or more passages 54 extend through the collar 51 at a point radiallyinwardly of the valve member 47.

As has been noted, FIG. 1 illustrates the cushioning unit 11 in itsnormal installed position. Impact forces applied to the cushioning unitfrom the coupler shank 12 or from the car frame structure 13 via thedraft lug assembly 34 tend to cause relative movement between the pistonassembly 21 and the cylinder assembly 14. This relative movement canonly be accomplished by forcing the oil through the orifice opening 41.If the valve assembly 43 were not provided, any force greater than theforce required to overcome the gas pressure in the chamber 19 wouldresult in such relative movement. Under low impact forces, such relativemovement is undesirable since it will result in considerable changes intrain length and attendant problems.

The valve 43, however, precludes any flow through the orifice opening 41by blocking the passage 44 until a predetermined force is applied. Whenthis predetermined force is reached, the pressure acting through thepassage 44 on the valve member 47 will cause its peripheral edge 48 todeflect away from the main piston 23 as shown in FIG. 2 and permit flow.The metering rod 39 and orifice opening 41 will provide fluid resistanceto continued movement, as is well known.

When the force is relieved, the valve member 47 will again move to itsclosed position. The gas pressure acting on the oil 53 will, however,cause the unit to return to its normal position (FIG. 1) since the oilcan be forced through the restricted passage 54 past the closed valveassembly 43. This return will occur at an extremely slow rate.

In the event a draft force is exerted on the cushioning unit 11 beforereturn to the normal position is reached, the cushioning unit 11 willalso be operative to resist such forces. Rapid runout will be precludedby the closure of the valve 43. If the draft force is sufficientlylarge, however, the valve member 47 will deflect so that its peripheralportion 49 moves away from the collar 51 (FIG. 3) and permits flow backthrough the opening 41. Thus, it should be readily apparent that thevalve assembly 43 acts as a pressure responsive valve for controllingflow in either direction through the orifice opening 41.

It is to be understood that the foregoing description is that of apreferred embodiment of the invention. Various changes and modificationsmay be made without departing from the spirit and scope of the inventionas defined by the appended claims.

I claim:

1. An end of car cushioning unit adapted to be interposed between acoupler and a car frame of a railway car for damping shock forces, saidcushioning unit comprising a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a chamber adapted toreceive a fluid, primary metering means in communication with saidchamber for passing fluid therethrough at a restricted rate uponrelative movement of said piston and said cylinder, and pressureresponsive valve means in series flow arrangement with said primarymetering means for precluding the flow of fluid through said primarymetering means until a predetermined force is applied to said cushioningunit.

2. An end of car cushioning unit adapted to be interposed between acoupler and a car frame of a railway car for damping shock forces, saidcushioning unit comprises a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a first chamber adaptedto receive a fluid, means defining a second chamber adapted to receive afluid, primary metering means in communication with said chamber forpassing fluid therethrough at a restricted rate upon relative movementof said piston and said cylinder, said primary metering means beingadapted to experience flow in one direction upon relative movement ofsaid piston and said cylinder in a first direction and in an oppositedirection upon relative movement of said piston and said cylinder in anopposite direction, and means for precluding the flow of fluid throughsaid primary metering means in each direction until a predeterminedforce is applied to said cushioning unit in the respective direction.

3. An end of car cushioning unit as set forth in claim 2 wherein themeans for precluding flow through the primary metering means comprisespressure responsive valve means.

4. An end ofcar cushioning unit as set forth in claim 3 wherein thepressure responsive valve means comprises a single valve element movablebetween a closed position and an open position in response to apredetermined pressure.

5. An end of car cushioning unit as set forth in claim 4 wherein thevalve element controls the flow in either direction through anassociated passage.

6. An end of car cushioning unit adapted to be interposed between acoupler and a car frame of a railway car for damping shock forces, saidcushioning unit comprising a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a chamber adapted toreceive a fluid, primary metering means in communication with saidchamber for passing fluid therethrough at a restricted rate uponrelative movement of said piston and said cylinder, said primarymetering means comprising an orifice and a cooperating metering rod, andmeans for precluding the flow of fluid through said primary meteringmeans until a predetermined force is applied to said cushioning unit.

7. An end of car cushioning unit as set forth in claim 6 wherein themeans for precluding flow through the primary metering means comprisespressure responsive valve means.

8. An end of car cushioning unit adapted to be interposed between acoupler and a car frame of a railway car for damping shock forces, saidcushioning unit comprising a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a chamber adapted toreceive a fluid and a gas under pressure acting on the contained fluidfor exerting a restoring force on said cushioning unit, primary meteringmeans in communication with said chamber for passing fluid therethroughat a restricted rate upon relative movement of said piston and saidcylinder, means for precluding the flow of fluid through said primarymetering means until a predetermined force is applied to said cushioningunit, and a bleed passage bypassing the means for precluding flowthrough said primary metering means for permitting a restricted rate offlow of the fluid.

9. A cushioning unit comprising a cylinder assembly defining the cavityadapted to receive a fluid, a piston supported for reciprocation withinsaid cavity, an orifice opening extending through said piston forcommunicating flow between opposite sides of said piston, a metering rodaffixed to said cavity and adapted to cooperate with said orifice, apassage extending through said piston in series with said orifice,pressure responsive valve means for controlling the flow through saidpassage for precluding flow through said orifice until a predeterminedforce is applied to said cushioning unit.

10. A cushioning unit as set forth in claim 9 wherein the pressureresponsive valve means comprises a conical spring disk having its outerperipheral edge adapted to sealingly engage a first portion of saidpiston on one side of said passage and its inner peripheral edge adaptedto engage a second portion of said piston on the other side of saidpassage.

11. A cushioning unit as set forth in claim 10 wherein the outerperipheral edge of the valve element is adapted to be deflected awayfrom the first portion of the piston under the influence of sufficientforce in one direction for precluding flow past said outer peripheraledge, the inner peripheral edge of said valve element being adapted todeflect away from sealing engagement with the second portion of thepiston upon the application of sufficient force in the oppositedirection to permit flow past said inner peripheral edge.

12. A cushioning unit as set forth in claim 11 further including a bleedpassage extending through said piston for permitting return flow offluid through the orifice at a restricted rate independently of thepressure responsive valve.

13. A damping apparatus comprising:

a cylinder having an elongated interior chamber with one end being openand the other end being closed;

a piston rod extending within said chamber, said piston rod beingmovable with respect to said chamber;

a piston head connected to said piston rod, said piston head including afirst member fixed to said piston rod and extending laterally therefrom,said first member located adjacent the wall of said chamber but spacedtherefrom to form a gap therebetween; damping medium located within saidchamber in between said piston head and said closed end; second membermounted upon said piston head, said second member capable of being incontact with both said first member and the wall of said chamber, saidsecond member includes means for permitting said first member to deflectin respect to said second member, upon a predetermined level of dampingforce being achieved said first member deflects thereby permitting saiddamping medium to be conducted through said gap past said first member.

14. The damping apparatus as defined in claim 13 wherein: said firstmember being annular, said gap being annular.

1. An end of car cushioning unit adapted to be interposed between acoupler and a car frame of a railway car for damping shock forces, saidcushioning unit comprising a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a chamber adapted toreceive a fluid, primary metering means in communication with saidchamber for passing fluid therethrough at a restricted rate uponrelative movement of said piston and said cylinder, and pressureresponsive valve means in series flow arrangement with said primarymetering means for precluding the flow of fluid through said primarymetering means until a predetermined force is applied to said cushioningunit.
 2. An end of car cushioning unit adapted to be interposed betweena coupler and a car frame of a railway car for damping shock forces,said cushioning unit comprises a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a first chamber adaptedto receive a fluid, means defining a second chamber adapted to receive afluid, primary metering means in communication with said chamber forpassing fluid therethrough at a restricted rate upon relative movementof said piston and said cylinder, said primary metering means beingadapted to experience floW in one direction upon relative movement ofsaid piston and said cylinder in a first direction and in an oppositedirection upon relative movement of said piston and said cylinder in anopposite direction, and means for precluding the flow of fluid throughsaid primary metering means in each direction until a predeterminedforce is applied to said cushioning unit in the respective direction. 3.An end of car cushioning unit as set forth in claim 2 wherein the meansfor precluding flow through the primary metering means comprisespressure responsive valve means.
 4. An end of car cushioning unit as setforth in claim 3 wherein the pressure responsive valve means comprises asingle valve element movable between a closed position and an openposition in response to a predetermined pressure.
 5. An end of carcushioning unit as set forth in claim 4 wherein the valve elementcontrols the flow in either direction through an associated passage. 6.An end of car cushioning unit adapted to be interposed between a couplerand a car frame of a railway car for damping shock forces, saidcushioning unit comprising a cylinder, a piston received within saidcylinder, said piston and said cylinder defining a chamber adapted toreceive a fluid, primary metering means in communication with saidchamber for passing fluid therethrough at a restricted rate uponrelative movement of said piston and said cylinder, said primarymetering means comprising an orifice and a cooperating metering rod, andmeans for precluding the flow of fluid through said primary meteringmeans until a predetermined force is applied to said cushioning unit. 7.An end of car cushioning unit as set forth in claim 6 wherein the meansfor precluding flow through the primary metering means comprisespressure responsive valve means.
 8. An end of car cushioning unitadapted to be interposed between a coupler and a car frame of a railwaycar for damping shock forces, said cushioning unit comprising acylinder, a piston received within said cylinder, said piston and saidcylinder defining a chamber adapted to receive a fluid and a gas underpressure acting on the contained fluid for exerting a restoring force onsaid cushioning unit, primary metering means in communication with saidchamber for passing fluid therethrough at a restricted rate uponrelative movement of said piston and said cylinder, means for precludingthe flow of fluid through said primary metering means until apredetermined force is applied to said cushioning unit, and a bleedpassage bypassing the means for precluding flow through said primarymetering means for permitting a restricted rate of flow of the fluid. 9.A cushioning unit comprising a cylinder assembly defining the cavityadapted to receive a fluid, a piston supported for reciprocation withinsaid cavity, an orifice opening extending through said piston forcommunicating flow between opposite sides of said piston, a metering rodaffixed to said cavity and adapted to cooperate with said orifice, apassage extending through said piston in series with said orifice,pressure responsive valve means for controlling the flow through saidpassage for precluding flow through said orifice until a predeterminedforce is applied to said cushioning unit.
 10. A cushioning unit as setforth in claim 9 wherein the pressure responsive valve means comprises aconical spring disk having its outer peripheral edge adapted tosealingly engage a first portion of said piston on one side of saidpassage and its inner peripheral edge adapted to engage a second portionof said piston on the other side of said passage.
 11. A cushioning unitas set forth in claim 10 wherein the outer peripheral edge of the valveelement is adapted to be deflected away from the first portion of thepiston under the influence of sufficient force in one direction forprecluding flow past said outer peripheral edge, the inner peripheraledge of said valve element being adapted to deflect away from sealingengagement with tHe second portion of the piston upon the application ofsufficient force in the opposite direction to permit flow past saidinner peripheral edge.
 12. A cushioning unit as set forth in claim 11further including a bleed passage extending through said piston forpermitting return flow of fluid through the orifice at a restricted rateindependently of the pressure responsive valve.
 13. A damping apparatuscomprising: a cylinder having an elongated interior chamber with one endbeing open and the other end being closed; a piston rod extending withinsaid chamber, said piston rod being movable with respect to saidchamber; a piston head connected to said piston rod, said piston headincluding a first member fixed to said piston rod and extendinglaterally therefrom, said first member located adjacent the wall of saidchamber but spaced therefrom to form a gap therebetween; a dampingmedium located within said chamber in between said piston head and saidclosed end; a second member mounted upon said piston head, said secondmember capable of being in contact with both said first member and thewall of said chamber, said second member includes means for permittingsaid first member to deflect in respect to said second member, upon apredetermined level of damping force being achieved said first memberdeflects thereby permitting said damping medium to be conducted throughsaid gap past said first member.
 14. The damping apparatus as defined inclaim 13 wherein: said first member being annular, said gap beingannular.